Field
Implementations described herein generally relate to semiconductor manufacturing. More specifically, implementations disclosed herein relate to silicon and aluminum containing layers.
Description of the Related Art
Semiconductor device geometries have dramatically decreased in size since such devices were first introduced several decades ago. Since then, integrated circuits have generally followed the two year/half-size rule (often called Moore's Law), which means that the number of devices that will fit on a chip doubles every two years. Today's fabrication plants are routinely producing devices having 0.35 μm and even 0.25 μm feature sizes, and tomorrow's plants soon will be producing devices having even smaller geometries.
With continued device scaling, interconnect RC delay continues escalating. Among several efforts being made to address this challenge, one is to lower the capacitance contributed by the dielectric diffusion barrier layer. This can be achieved by either lowering the dielectric constant or physically thinning down the barrier. There are trade-offs with each approach.
Low dielectric constant (low k) barriers are generally less dense materials which limit their ability to function as robust barrier to oxidation, moisture penetration, and Cu diffusion. On the other hand, physically thinning down the barrier is constrained by the ability of the thin layer to serve as an effective etch stop layer, especially given micro-loading and non-uniformity of dry etch processes. In this context, traditional SiCN or SiOC based barrier/etch stop layers have reached their scaling limit.
Bilayer of SiCN or SiOC with alternative materials with much higher dry/etch etch selectivity than SiCN/SiOC have been considered in order to continue scaling effective capacitance while affording adequate etch stop protection. From this perspective, aluminum nitride (AlN) is an attractive alternative material. AlN has excellent selectivity to ultra low k (ULK) etch, good insulating properties and reasonable dielectric constant of 8-9. However, while AlN is a good etch stop layer, it is not hermetic. Conversely, SiCN or SiN are hermetic but limited in their etch stop capability.
Therefore, a there is a need for new layers for BEOL processes.